Which hazard descriptor describes a material that can ignite spontaneously in air?

Which hazard descriptor describes a material that can ignite spontaneously in air?

• A. Non-flammable compressed gas
• B. Explosive
• C. Spontaneously Combustible
• D. Radioactive substance

Answer: (C)

Spontaneously combustible describes materials that can ignite on their own in air, without an external flame or spark. This happens when a substance undergoes oxidation or a chemical reaction that generates heat fast enough that the heat isn’t dissipated, causing the material to reach its ignition temperature and catch fire. It’s a specific hazard descriptor used to warn that the material can start burning by itself under normal conditions, especially if there’s a buildup of heat or if it’s stored improperly. Non-flammable compressed gas isn’t prone to ignition, so it doesn’t carry this descriptor. An explosive is about a rapid energy release that may occur with a spark, shock, or heat, but it isn’t defined by self-heating and ignition in air. A radioactive substance relates to radiation hazards, not ignition behavior.

Spontaneously combustible describes materials that can ignite on their own in air, without an external flame or spark. This happens when a substance undergoes oxidation or a chemical reaction that generates heat fast enough that the heat isn’t dissipated, causing the material to reach its ignition temperature and catch fire. It’s a specific hazard descriptor used to warn that the material can start burning by itself under normal conditions, especially if there’s a buildup of heat or if it’s stored improperly.

Non-flammable compressed gas isn’t prone to ignition, so it doesn’t carry this descriptor. An explosive is about a rapid energy release that may occur with a spark, shock, or heat, but it isn’t defined by self-heating and ignition in air. A radioactive substance relates to radiation hazards, not ignition behavior.